JP7520566B2 - Zoom lens and imaging device - Google Patents

Description

The present invention relates to a zoom lens suitable for imaging devices such as video cameras, electronic still cameras, broadcast cameras, surveillance cameras, and silver halide film cameras.

As a zoom lens that can obtain a high zoom ratio, Patent Documents 1 and 2 disclose a zoom lens that is composed of, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and multiple subsequent lens groups.

JP 2016-139125 A JP 2001-108902 A

In order to achieve good optical performance and a bright F-number in a high zoom ratio zoom lens having a configuration such as those disclosed in Patent Documents 1 and 2, it is important to appropriately set the arrangement of positive and negative refractive powers, the lens groups that are moved during zooming, and the lens groups that are moved during focusing.

The present invention provides a zoom lens having a high zoom ratio, good optical performance and a bright F-number, and an imaging device having the same.

A zoom lens according to one aspect of the present invention is composed of, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with negative refractive power, a sixth lens group with positive refractive power, and a seventh lens group with negative refractive power. During zooming, the distance between adjacent lens groups changes, the first lens group and the second lens group move, a plurality of lens groups among the third lens group to the seventh lens group move, and at least one lens group among the fourth lens group to the seventh lens group remains stationary. When the focal length of the third lens group is f3 and the focal length of the fourth lens group is f4,
0.440≦f3/f4≦3.443
The present invention is characterized in that it satisfies the following conditions.

The present invention provides a zoom lens with a high zoom ratio, good optical performance, and a bright F-number.

FIG. 1 is a cross-sectional view of a zoom lens according to a first embodiment. 4A to 4C are aberration diagrams of the zoom lens of Example 1 at the wide-angle end, at a middle zoom position, and at a telephoto end when the zoom lens is focused on an infinity distance. FIG. 11 is a cross-sectional view of a zoom lens according to a second embodiment. 11A to 11C are aberration diagrams of the zoom lens of Example 2 at the wide-angle end, at the intermediate zoom position, and at the telephoto end when the lens is focused on an infinity distance. FIG. 11 is a cross-sectional view of a zoom lens according to a third embodiment. 11A to 11C are aberration diagrams of the zoom lens of Example 3 at the wide-angle end, at the intermediate zoom position, and at the telephoto end when the zoom lens is focused on an infinity distance. FIG. 11 is a cross-sectional view of a zoom lens according to a fourth embodiment. 13A to 13C are aberration diagrams of the zoom lens of Example 4 when focused on infinity at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. FIG. 13 is a cross-sectional view of a zoom lens according to a fifth embodiment. 13A to 13C are aberration diagrams of the zoom lens of Example 5 when focused on infinity at (A) the wide-angle end, (B) a middle zoom position, and (C) a telephoto end. FIG. 1 is a schematic diagram of an imaging device including the zoom lenses according to the first to fifth embodiments.

Below, an embodiment of the present invention will be described with reference to the drawings. The zoom lens of the embodiment of the present invention has, arranged in order from the object side to the image side, a first lens group with positive refractive power (the reciprocal of the focal length), a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, a fifth lens group with negative refractive power, a sixth lens group with positive refractive power, and a seventh lens group with negative refractive power. In this zoom lens, when zooming between the wide-angle end and the telephoto end, the whole or part of the first lens group and several lens groups among the second to seventh lens groups move in the optical axis direction. In addition, at least one of the fourth to seventh lens groups is immobile (fixed) during zooming. Note that a lens group is a group of one or more lenses whose spacing from the preceding and following lens groups changes during zooming or focusing.

Figures 1, 3, 5, 7, and 9 respectively show cross sections of the zoom lenses of Examples 1 to 5 at the wide-angle end (shortest focal length state) and the telephoto end (longest focal length state). The wide-angle end and the telephoto end refer to the states (zoom positions) when the lens group is located at both ends of the range in which it can move mechanically in the optical axis direction during zooming.

In these figures, the left side is the object side (front side) and the right side is the image side (rear side). If i is the order of the lens groups from the object side to the image side, Bi indicates the i-th lens group. The subgroups included in the first lens group B1 are indicated as the 1A lens group B1A and the 1B lens group B1B in order from the object side. The 1A lens group B1A and the 1B lens group B1B may have positive or negative refractive powers, respectively, as long as the sign of their composite refractive power is positive. Furthermore, it is sufficient that at least one of the 1A lens group B1A and the 1B lens group B1B moves during zooming. Note that in Examples 4 and 5 described later, the 1A lens group B1A and the 1B lens group B1B both have positive refractive power, and the 1A lens group B1A moves during zooming, and the 1B lens group B1B does not move.

The solid arrows below the lens groups that move during zooming indicate the movement trajectory of each lens group when zooming from the wide-angle end to the telephoto end. Also, the dotted arrows below the focus lens group that moves during focusing indicate the movement trajectory when focusing from infinity to a close distance.

The aperture stop SP determines the light flux of the open F-number (Fno). GB is an optical block equivalent to an optical filter, face plate, low-pass filter, infrared cut filter, etc. IP is the image plane. On the image plane IP, the imaging surface of a solid-state imaging element (photoelectric conversion element) such as a CCD sensor or CMOS sensor, or the film surface of a silver halide film is placed.

In the zoom lens of Example 1 shown in FIG. 1, the entire first lens group B1 and the second, third, fifth and seventh lens groups B2, B3, B5 and B7 move during zooming, while the fourth and sixth lens groups B4 and B6 are stationary. The aperture stop SP is located closest to the object in the third lens group B3.

Examples of numerical values of the zoom lens of Example 1 are described later as Numerical Example 1. The zoom lens of Example 1 (Numerical Example 1) is a bright telephoto zoom lens with a high zoom ratio, with a zoom ratio of 2.6x, an F-number indicating the brightness of the zoom lens of approximately 2.88, and a half angle of view ω of approximately 16 degrees to 6 degrees.

In the zoom lens of Example 2 shown in FIG. 3, the entire first lens group B1 and the second, third, fifth and seventh lens groups B2, B3, B5 and B7 move during zooming, while the fourth and sixth lens groups B4 and B6 remain stationary. The aperture stop SP is provided between the second lens group B2 and the third lens group B3.

Examples of the various numerical values of the zoom lens of Example 2 are described later as Numerical Example 2. The zoom lens of Example 2 (Numerical Example 2) is a bright telephoto zoom lens with a high zoom ratio, with a zoom ratio of 2.6x, an F-number of approximately 2.88, and a half angle of view ω of approximately 16 degrees to 6 degrees.

In the zoom lens of Example 3 shown in FIG. 5, the entire first lens group B1 and the second, third, fifth and seventh lens groups B2, B3, B5 and B7 move during zooming, while the fourth and sixth lens groups B4 and B6 are stationary. The aperture stop SP is located closest to the object in the third lens group B3.

Examples of the various numerical values of the zoom lens of Example 3 are described later as Numerical Example 3. The zoom lens of Example 3 (Numerical Example 3) is a bright telephoto zoom lens with a high zoom ratio, with a zoom ratio of 2.6x, an F-number of approximately 2.88, and a half angle of view ω of approximately 16 degrees to 6 degrees.

In the zoom lens of Example 4 shown in FIG. 7, the first lens group B1 is composed of the first A lens group B1A and the first B lens group B1B, and during zooming, the first A lens group B1A and the second, third, fifth and seventh lens groups B2, B3, B5 and B7 move, while the first B, fourth and sixth lens groups B1B, B4 and B6 do not move. The aperture stop SP is provided closest to the object in the fourth lens group B4.

Examples of the various numerical values of the zoom lens of Example 4 are described later as Numerical Example 3. The zoom lens of Example 4 (Numerical Example 4) is a bright telephoto zoom lens with a high zoom ratio, with a zoom ratio of 2.6 times, an F-number of approximately 2.88, and a half angle of view ω of approximately 16 degrees to 6 degrees.

In the zoom lens of Example 5 shown in FIG. 9, the first lens group B1 is composed of the first A lens group B1A and the first B lens group B1B, and during zooming, the first A lens group B1A and the second, third, fifth and seventh lens groups B2, B3, B5 and B7 move, while the first B, fourth and sixth lens groups B1B, B4 and B6 do not move. The aperture stop SP is provided closest to the object in the third lens group B3.

Examples of numerical values of the zoom lens of Example 5 are described later as Numerical Example 5. The zoom lens of Example 5 (Numerical Example 5) is a bright telephoto zoom lens with a high zoom ratio, with a zoom ratio of 2.6x, an F-number of approximately 2.88, and a half angle of view ω of approximately 16 degrees to 6 degrees.

The zoom lenses of the embodiments are used as imaging optical systems in imaging devices such as video cameras, digital still cameras, silver halide film cameras, and TV cameras, but can also be used as projection optical systems in image projection devices (projectors) that have light modulation elements such as liquid crystal panels and digital micromirror devices. In this case, in the cross-sectional view of the zoom lens, the left side is the object side (projection surface side) and the right side is the image side (light modulation element side).

Figures 2(A), (B), (C), 4(A), (B), (C), 6(A), (B), (C), 8(A), (B), (C), and 10(A), (B), (C) are aberration diagrams of the zoom lenses of Examples 1 to 5 at (A) the wide-angle end, (B) the intermediate zoom position, and (C) the telephoto end when focused on infinity, respectively.

In the spherical aberration diagram, Fno indicates the F-number, the solid line indicates the spherical aberration for the d-line (wavelength 587.6 nm), and the two-dot chain line indicates the spherical aberration for the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line S indicates the sagittal image plane, and the dashed line M indicates the meridional image plane. Distortion aberration is shown for the d-line. The chromatic aberration diagram shows the chromatic aberration of magnification for the g-line. ω is the half angle of view (°).

In general, a zoom lens that is composed of, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with strong negative refractive power, a third lens group with positive refractive power, and multiple subsequent lens groups, is likely to achieve a high zoom ratio while being small in size. The zoom lens of each embodiment has, as the subsequent lens groups, in order from the object side to the image side, a fourth lens group B4 with positive refractive power, a fifth lens group B5 with negative refractive power, a sixth lens group B6 with positive refractive power, and a seventh lens group B7 with negative refractive power, thereby achieving a small size, a high zoom ratio, a bright F-number, and suppression of various aberrations.

In addition, the zoom lens of each embodiment shortens the overall lens length at the wide-angle end by moving all or part of the first lens group B1 toward the object side when zooming from the wide-angle end to the telephoto end. Furthermore, by moving multiple lens groups among the second to seventh lens groups B2-B3 in the optical axis direction, a high zoom ratio is achieved while suppressing fluctuations in various aberrations. At this time, by keeping at least one lens group among the fourth to seventh lens groups B4-B7 stationary, the configuration of the drive mechanism that moves the lens groups during zooming is simplified, and a compact optical device having a zoom lens is achieved. In each embodiment, at least the fourth and sixth lens groups B4 and B6 are stationary during zooming.

In the zoom lens of each embodiment, the negative fifth lens group B5 is moved during focusing. Since the fifth lens group B5 is the smallest lens group among the first to seventh lens groups B1 to B7, the drive mechanism for the fifth lens group B5 can be made compact during focusing.

In the zoom lenses of each embodiment, the third lens group B3 and the fourth lens group B4 are each composed of two positive lenses and one negative lens. Since the third lens group B3 and the fourth lens group B4 are the lens groups with the largest axial ray diameters among the first to seventh lens groups B1 to B7, it is preferable to compose them with multiple lenses to correct spherical aberration and axial chromatic aberration. Note that only one of the third lens group B3 and the fourth lens group B4 may be composed of two positive lenses and one negative lens.

In addition, in the zoom lens of each embodiment, when the focal length of the positive first lens unit B1 (or the composite focal length of the 1A and 1B lens units) is f1 and the focal length of the negative second lens unit B2 is f2, it is preferable that the following conditional expression (1) be satisfied:
1.440≦f1/｜f2｜≦3.260 (1)
Conditional formula (1) shows a condition related to the ratio between the focal length of the first lens group B1 (the first-A and first-B lens groups B1A and B1B) and the absolute value of the focal length of the second lens group B2. If the focal length of the first lens group B1 becomes too large so that f1/|f2| exceeds the upper limit of conditional formula (1), it becomes easy to correct aberrations, but the amount of movement of the first lens group B1 (or the first-A lens group B1A) during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the focal length of the first lens group B1 becomes too small so that f1/|f2| falls below the lower limit of conditional formula (1), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct spherical aberration, especially at the telephoto end, which is not preferable.

In addition, it is preferable that the zoom lens of each embodiment satisfies the following conditional expression (2), where the focal length of the negative second lens unit B2 is f2 and the back focus at the wide-angle end of the zoom lens is wsk.
1.690≦|f2|/wsk≦5.990 (2)
Conditional formula (2) shows a condition related to the ratio between the absolute value of the focal length of the second lens group B2 and the back focus at the wide-angle end. If the absolute value of the focal length of the second lens group B2 becomes too large so that |f2|/wsk exceeds the upper limit of conditional formula (2), it becomes easy to correct aberrations, but the amount of movement of the second lens group B2 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the absolute value of the focal length of the second lens group B2 becomes too small so that |f2|/wsk falls below the lower limit of conditional formula (2), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct field curvature and distortion aberrations, especially at the wide-angle end, which is not preferable.

In the zoom lens of each embodiment, it is preferable that the following conditional expression (3) be satisfied, where the focal length of the positive third lens unit B2 is f3 and the focal length of the positive fourth lens unit B4 is f4.
0.440≦f3/f4≦4.350 (3)
Conditional formula (3) shows a condition related to the ratio of the focal length of the third lens group B3 to the focal length of the fourth lens group B4. If the focal length of the third lens group B3 becomes too large so that f3/f4 exceeds the upper limit of conditional formula (3), it becomes easy to correct aberrations, but the amount of movement of the third lens group B3 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the focal length of the third lens group B3 becomes too small so that f3/f4 falls below the lower limit of conditional formula (3), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct spherical aberration and axial chromatic aberration, especially at the telephoto end, which is not preferable.

In addition, in the zoom lens of each embodiment, when the focal length of the positive first lens unit B1 (or the composite focal length of the 1A and 1B lens units B1A and B1B) is f1 and the focal length of the negative fifth lens unit B5 is f5, it is preferable that the following conditional expression (4) be satisfied:
1.850≦f1/｜f5｜≦9.230 (4)
Conditional expression (4) shows a condition regarding the absolute value and ratio of the focal length of the first lens group B1 (the first A and first B lens groups B1A and B1B) and the focal length of the fifth lens group B5. If the absolute value of the focal length of the fifth lens group B5 becomes too large so that f1/|f5| exceeds the upper limit of conditional expression (4), it becomes easy to correct aberrations, but the amount of movement of the fifth lens group B5 during focusing becomes large, and the zoom lens becomes large, which is not preferable. If the absolute value of the focal length of the fifth lens group B5 becomes too small so that f1/|f5| falls below the lower limit of conditional expression (4), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct spherical aberration and curvature of field when focusing at a close distance, which is not preferable.

In the zoom lens of each embodiment, it is preferable that the following conditional expression (5) be satisfied, where the focal length of the positive sixth lens unit B6 is f6 and the focal length of the negative seventh lens unit B7 is f7.
0.340≦f6/｜f7｜≦0.900 (5)
Conditional expression (5) shows a condition related to the ratio between the focal length of the sixth lens group B6 and the absolute value of the focal length of the seventh lens group B7. If the absolute value of the focal length of the seventh lens group B7 becomes too large so that f6/|f7| exceeds the upper limit of conditional expression (5), it becomes easy to correct aberrations, but the amount of movement of the seventh lens group B7 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the absolute value of the focal length of the seventh lens group B7 becomes too small so that f6/|f7| falls below the lower limit of conditional expression (5), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct the fluctuation of the field curvature during zooming, which is not preferable.

In addition, in the zoom lens of each embodiment, when the focal length of the positive first lens unit B1 (or the composite focal length of the 1A and 1B lens units B1A and B1B) is f1 and the focal length of the positive third lens unit B3 is f3, it is preferable that the following conditional expression (6) be satisfied:
0.590≦f1/f3≦4.110 (6)
Conditional expression (6) indicates a condition related to the ratio of the focal length of the first lens group B1 (the first-A and first-B lens groups B1A and B1B) to the focal length of the third lens group B3. If the focal length of the first lens group B1 becomes too large so that f1/f3 exceeds the upper limit of conditional expression (6), it becomes easy to correct aberrations, but the amount of movement of the first lens group B1 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the focal length of the first lens group B1 becomes too small so that f1/f3 falls below the lower limit of conditional expression (6), it is effective in reducing the size of the zoom lens, but it becomes difficult to correct spherical aberration and axial chromatic aberration, especially at the telephoto end, which is not preferable.

In addition, in the zoom lens of each embodiment, when the focal length of the positive first lens unit B1 (or the composite focal length of the 1A and 1B lens units B1A and B1B) is f1 and the focal length of the negative seventh lens unit B7 is f7, it is preferable that the following conditional expression (7) be satisfied:
1.150≦f1/｜f7｜≦3.460 (7)
Conditional expression (7) shows a condition related to the ratio of the focal length of the first lens group B1 (the first A and first B lens groups B1A and B1B) to the absolute value of the focal length of the seventh lens group B7. If the absolute value of the focal length of the seventh lens group B7 becomes too large so that f1/|f7| exceeds the upper limit of conditional expression (7), it becomes easy to correct aberrations, but the amount of movement of the seventh lens group B7 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the absolute value of the focal length of the seventh lens group B7 becomes too small so that f1/|f7| falls below the lower limit of conditional expression (7), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct the fluctuation of the field curvature during zooming, which is not preferable.

In the zoom lens of each embodiment, it is preferable to satisfy the following conditional expression (8), where the focal length of the negative second lens unit B2 is f2 and the focal length of the positive sixth lens unit B6 is f6.
0.720≦|f2|/f6≦2.780 (8)
Conditional expression (8) shows a condition related to the ratio between the absolute value of the focal length of the second lens group B2 and the focal length of the sixth lens group B6. If the absolute value of the focal length of the second lens group B2 becomes too large so that |f2|/f6 exceeds the upper limit of conditional expression (8), it becomes easy to correct aberrations, but the amount of movement of the second lens group B2 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the absolute value of the focal length of the second lens group B2 becomes too small so that |f2|/f6 falls below the lower limit of conditional expression (8), it is effective for size reduction, but it becomes difficult to correct fluctuations in field curvature, especially at the wide-angle end, which is not preferable.

In the zoom lens of each embodiment, it is preferable to satisfy the following conditional expression (9), where the focal length of the negative seventh lens unit B7 is f7 and the back focus at the wide-angle end is wsk.
2.370≦|f7|/wsk≦5.650 (9)
Conditional expression (9) shows a condition related to the ratio between the absolute value of the focal length of the seventh lens group B7 and the back focus at the wide-angle end. If the absolute value of the focal length of the seventh lens group B7 becomes too large so that |f7|/wsk exceeds the upper limit of conditional expression (9), it becomes easy to correct aberrations, but the amount of movement of the seventh lens group B7 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the absolute value of the focal length of the seventh lens group B7 becomes too small so that |f7|/wsk falls below the lower limit of conditional expression (9), it is effective for size reduction, but it becomes difficult to correct fluctuations in field curvature, especially at the wide-angle end, which is not preferable.

In the zoom lens of each embodiment, it is preferable that the following conditional expression (10) be satisfied, where the focal length of the positive third lens unit B3 is f3 and the focal length of the negative second lens unit B2 is f2.
0.550≦f3/｜f2｜≦3.560 (10)
Conditional expression (10) shows a condition related to the ratio between the focal length of the third lens group B3 and the absolute value of the focal length of the second lens group B2. If the focal length of the third lens group B3 becomes too large so that f3/|f2| exceeds the upper limit of conditional expression (10), the amount of movement of the third lens group B3 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the focal length of the third lens group B3 becomes too small so that f3/|f2| falls below the lower limit of conditional expression (10), it is effective for miniaturizing the zoom lens, but it is not preferable because it becomes difficult to correct spherical aberration, especially at the telephoto end.

In addition, it is preferable that the zoom lens of each embodiment satisfies the following conditional expression (11), where the focal length of the negative second lens unit B2 is f2 and the focal length of the entire zoom lens system at the wide-angle end is fw.
0.430≦|f2|/fw≦1.640 (11)
Conditional expression (11) shows a condition related to the ratio between the absolute value of the focal length of the second lens group B2 and the focal length of the entire system at the wide-angle end. If the absolute value of the focal length of the second lens group B2 becomes too large so that |f2|/fw exceeds the upper limit of conditional expression (11), it becomes easy to correct aberrations, but the amount of movement of the second lens group B2 during zooming becomes large, and the zoom lens becomes large, which is not preferable. If the absolute value of the focal length of the second lens group B2 becomes too small so that |f2|/fw falls below the lower limit of conditional expression (11), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct spherical aberration, especially at the wide-angle end, which is not preferable.

In addition, it is preferable that the zoom lens of each embodiment satisfies the following conditional expression (12), where the focal length of the negative fifth lens unit B5 is f5 and the focal length of the entire zoom lens system at the telephoto end is ft.
0.110≦|f5|/ft≦0.310 (12)
Conditional expression (12) shows a condition related to the ratio between the absolute value of the focal length of the fifth lens group B5 and the focal length of the entire system at the telephoto end. If the absolute value of the focal length of the fifth lens group B5 becomes too large so that |f5|/ft exceeds the upper limit of conditional expression (12), it becomes easy to correct aberrations, but the amount of movement of the fifth lens group B5 during focusing becomes large, which is not preferable. If the absolute value of the focal length of the fifth lens group B5 becomes too small so that |f5|/ft falls below the lower limit of conditional expression (12), it is effective for miniaturizing the zoom lens, but it becomes difficult to correct the fluctuation of the field curvature, especially at the wide-angle end, which is not preferable.

In addition, it is preferable that the zoom lens of each embodiment satisfies the following conditional expression (13), where the focal length of the positive sixth lens unit B6 is f6 and the focal length of the entire zoom lens system at the telephoto end is ft.
0.150≦f6/ft≦0.320 (13)
Conditional expression (13) shows a condition related to the ratio of the focal length of the sixth lens group B6 to the focal length of the entire system at the telephoto end. If the focal length of the sixth lens group B6 becomes too long so that f6/ft exceeds the upper limit of conditional expression (13), it is difficult to correct mainly lateral chromatic aberration, which is not preferable. If the focal length of the sixth lens group B6 becomes too short so that f6/ft falls below the lower limit of conditional expression (13), it is effective for miniaturizing the zoom lens, but it is not preferable because it is difficult to correct the fluctuation of field curvature, especially at the wide-angle end.

By satisfying any of the above conditional expressions, it is possible to realize a compact telephoto zoom lens with a high zoom ratio, good optical performance across the entire zoom range, and a bright Fno. In addition, in the zoom lenses of each embodiment, all lens groups are constructed using only spherical lenses, eliminating the use of aspherical lenses, which are expensive to manufacture.

It is more preferable to set the numerical ranges of the conditional expressions (1) to (13) as follows:
1.850≦f1/｜f2｜≦2.760 (1a)
2.170≦|f2|/wsk≦5.070 (2a)
0.570≦f3/f4≦3.680 (3a)
2.370≦f1/｜f5｜≦7.810 (4a)
0.440≦f6/｜f7｜≦0.760 (5a)
0.760≦f1/f3≦3.480 (6a)
1.480≦f1/｜f7｜≦2.930 (7a)
0.930≦|f2|/f6≦2.350 (8a)
3.050≦|f7|/wsk≦4.780 (9a)
0.710≦f3/｜f2｜≦3.010 (10a)
0.550≦|f2|/fw≦1.390 (11a)
0.140≦|f5|/ft≦0.260 (12a)
0.190≦f6/ft≦0.270 (13a)
It is more preferable to set the numerical ranges of the conditional expressions (1) to (13) as follows:
2.003≦f1/｜f2｜≦2.580 (1b)
2.344≦|f2|/wsk≦4.744 (2b)
0.615≦f3/f4≦3.443 (3b)
2.563≦f1/｜f5｜≦7.312 (4b)
0.480≦f6/｜f7｜≦0.708 (5b)
0.820≦f1/f3≦3.252 (6b)
1.597≦f1/｜f7｜≦2.735 (7b)
1.006≦|f2|/f6≦2.200 (8b)
3.290≦|f7|/wsk≦4.474 (9b)
0.770≦f3/｜f2｜≦2.818 (10b)
0.600≦|f2|/fw≦1.296 (11b)
0.160≦|f5|/ft≦0.242 (12b)
0.213≦f6/ft≦0.250 (13b)
In the first to fifth embodiments, the zoom lens is composed of seven lens groups. However, the zoom lens may have eight or more lens groups and satisfy the above conditional expressions.

Numerical examples 1 to 5 are shown below. In each numerical example, ri is the radius of curvature (mm) of the ith surface from the object side, di is the lens thickness or air space (mm) between the ith and (i+1)th surfaces, and ndi is the refractive index at the d-line of the material of the ith optical component. The two surfaces closest to the image correspond to the glass block G.

νdi is the Abbe number based on the d-line of the material of the i-th optical component. The Abbe number νd is expressed as νd = (Nd-1)/(NF-NC), where Nd, NF, and NC are the refractive indices at the d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) of the Fraunhofer lines.

sk represents the back focus (mm). "Back focus" is the distance on the optical axis from the final surface of the zoom lens (the lens surface closest to the image) to the paraxial image surface, expressed as an air-equivalent length. "Total lens length" is the distance on the optical axis from the foremost surface of the zoom lens (the surface closest to the object) to the final surface (the surface closest to the image) plus the back focus. In conditional expressions (2) and (9), wsk is sk at the wide-angle end.

Furthermore, fi indicates the focal length of the i-th lens group. Wide angle indicates the wide-angle end, intermediate indicates the intermediate zoom position, and telephoto indicates the telephoto end. When the first lens group is composed of a subgroup of the 1A lens group and the 1B lens group, the composite focal length of the 1A lens group and the 1B lens group at the wide-angle end is indicated as f1.

Table 1 shows the values corresponding to the above-mentioned conditional expressions (1) to (13) in Examples (Numerical Examples) 1 to 5.
[Numerical Example 1]
Unit: mm

Surface data surface number rd nd νd
1 90.003 2.90 1.96300 24.1
2 75.417 9.65 1.43875 94.7
3 10149.843 1.00
4 146.037 3.75 1.49700 81.5
5 381.317 (variable)
6 -301.093 1.50 1.54814 45.8
7 61.756 3.57
8 -89.325 1.50 1.56883 56.4
9 64.995 3.19 2.00069 25.5
10 330.239 (variable)
11 (Aperture) ∞ 1.00
12 68.358 4.58 1.88300 40.8
13 -142.212 1.89
14 -51.004 1.50 1.72825 28.5
15 76.339 0.20
16 55.898 2.83 1.88300 40.8
17 127.283 (variable)
18 -430.797 3.72 2.00330 28.3
19 -54.144 0.20
20 51.607 6.89 1.59522 67.7
21 -42.119 1.70 2.00069 25.5
22 378.571 (variable)
23 212.672 4.61 1.92286 20.9
24 -36.603 1.30 1.90525 35.0
25 32.588 (variable)
26 45.416 8.91 1.51633 64.1
27 -48.964 (variable)
28 -52.572 1.80 1.88300 40.8
29 -314.780 (variable)
30 ∞ 0.20 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Various data Zoom ratio 2.67
Wide Angle Mid Telephoto Focal Length 73.00 135.00 195.00
F-number 2.88 2.88 2.88
Half angle of view (°) 16.51 9.10 6.33
Image height 21.64 21.64 21.64
Lens total length 178.20 203.73 216.21
sk 19.12 26.34 33.67

d 5 3.83 54.60 79.43
d10 42.38 18.48 2.00
d17 5.62 4.28 8.42
d22 11.33 7.58 2.00
d25 7.34 11.09 16.67
d27 20.38 13.17 5.83
d29 15.00 22.21 29.55
d31 3.99 3.99 3.99

Zoom lens data group Starting surface Focal length
1 1 171.11
2 6 -73.71
3 11 195.87
4 18 58.61
5 23 -44.28
6 26 47.15
7 28 -71.71
8 30∞

[Numerical Example 2]
Unit: mm

Surface data surface number rd nd νd
1 82.966 2.90 2.00069 25.5
2 69.557 10.16 1.43875 94.7
3 2233.248 1.00
4 153.356 3.58 1.53775 74.7
5 389.429 (variable)
6 -322.755 1.50 1.54072 47.2
7 61.557 6.16
8 -83.812 1.50 1.56384 60.7
9 65.479 3.16 2.00069 25.5
10 304.050 (variable)
11 (Aperture) ∞ (Variable)
12 65.027 4.80 1.85150 40.8
13 -138.057 1.77
14 -51.477 1.50 1.74077 27.8
15 61.753 0.20
16 51.535 3.48 1.88300 40.8
17 194.910 (variable)
18 -402.524 3.64 2.00330 28.3
19 -54.926 0.20
20 51.153 7.06 1.60311 60.6
21 -39.556 1.70 2.00069 25.5
22 379.488 (variable)
23 236.282 5.17 1.92286 20.9
24 -31.120 1.30 1.90525 35.0
25 31.079 (variable)
26 43.402 9.23 1.51633 64.1
27 -46.442 (variable)
28 -51.385 1.80 1.90043 37.4
29 -293.245 (variable)
30 ∞ 0.20 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Various data Zoom ratio 2.67
Wide Angle Mid Telephoto Focal Length 73.00 135.00 195.00
F-number 2.88 2.88 2.88
Half angle of view (°) 16.51 9.10 6.33
Image height 21.64 21.64 21.64
Lens length 178.20 204.60 216.83
sk 19.93 27.06 34.02

d 5 3.83 52.89 75.63
d10 35.16 12.50 2.00
d11 6.96 7.19 2.00
d17 4.53 4.30 9.49
d22 10.36 6.94 2.00
d25 6.76 10.18 15.12
d27 18.85 11.72 4.77
d29 13.78 20.91 27.87
d31 6.02 6.02 6.02

Zoom lens data group Starting surface Focal length
1 1 167.28
2 6 -71.23
3 12 158.71
4 18 60.44
5 23 -41.21
6 26 45.03
7 28 -69.44
8 30∞

[Numerical Example 3]
Unit: mm

Surface data surface number rd nd νd
1 82.966 2.90 2.00069 25.5
2 69.557 10.16 1.43875 94.7
3 2233.248 1.00
4 153.356 3.58 1.53775 74.7
5 389.429 (variable)
6 -322.755 1.50 1.54072 47.2
7 61.557 6.16
8 -83.812 1.50 1.56384 60.7
9 65.479 3.16 2.00069 25.5
10 304.050 (variable)
11 (Aperture) ∞ (Variable)
12 65.027 4.80 1.85150 40.8
13 -138.057 1.77
14 -51.477 1.50 1.74077 27.8
15 61.753 0.20
16 51.535 3.48 1.88300 40.8
17 194.910 (variable)
18 -402.524 3.64 2.00330 28.3
19 -54.926 0.20
20 51.153 7.06 1.60311 60.6
21 -39.556 1.70 2.00069 25.5
22 379.488 (variable)
23 236.282 5.17 1.92286 20.9
24 -31.120 1.30 1.90525 35.0
25 31.079 (variable)
26 43.402 9.23 1.51633 64.1
27 -46.442 (variable)
28 -51.385 1.80 1.90043 37.4
29 -293.245 (variable)
30 ∞ 0.20 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Various data Zoom ratio 2.67
Wide Angle Mid Telephoto Focal Length 73.00 135.00 195.00
F-number 2.88 2.88 2.88
Half angle of view (°) 16.51 9.10 6.33
Image height 21.64 21.64 21.64
Lens length 178.20 204.60 216.83
sk 19.93 27.06 34.02

d 5 3.83 52.89 75.63
d10 35.16 12.50 2.00
d11 6.96 7.19 2.00
d17 4.53 4.30 9.49
d22 10.36 6.94 2.00
d25 6.76 10.18 15.12
d27 18.85 11.72 4.77
d29 13.78 20.91 27.87
d31 6.02 6.02 6.02

Zoom lens data group Starting surface Focal length
1 1 167.28
2 6 -71.23
3 12 158.71
4 18 60.44
5 23 -41.21
6 26 45.03
7 28 -69.44
8 30∞

[Numerical Example 4]
Unit: mm

Surface data surface number rd nd νd
1 92.312 2.90 1.85478 24.8
2 70.088 10.66 1.43875 94.7
3 -2073.607 (variable)
4 69.082 7.62 1.49700 81.5
5 500.594 (variable)
6 -27099.337 1.50 1.63930 44.9
7 55.029 3.81
8 -103.351 1.50 1.71999 50.2
9 42.906 3.81 1.89286 20.4
10 129.140 (variable)
11 77.231 5.02 1.85150 40.8
12 -89.699 1.28
13 -51.648 1.50 1.74077 27.8
14 57.745 0.20
15 54.109 3.45 2.00100 29.1
16 234.314 (variable)
17(Aperture) ∞ 2.08
18 -1442.673 3.80 1.90043 37.4
19 -56.569 0.20
20 44.027 7.02 1.59522 67.7
21 -43.323 1.70 2.00069 25.5
22 300.867 (variable)
23 387.579 3.63 1.85896 22.7
24 -38.061 1.30 1.85150 40.8
25 30.465 (variable)
26 58.401 8.23 1.56883 56.4
27 -40.643 (variable)
28 -50.173 1.80 1.88300 40.8
29 -500.000 (variable)
30 ∞ 0.20 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Various data Zoom ratio 2.67
Wide Angle Mid Telephoto Focal Length 73.00 130.00 195.00
F-number 2.88 2.88 2.88
Half angle of view (°) 16.51 9.45 6.33
Image height 21.64 21.64 21.64
Lens total length 178.20 190.55 198.20
sk 18.65 25.30 33.73

d 3 1.00 13.35 21.00
d 5 3.00 24.57 37.92
d10 34.13 17.53 4.18
d16 6.98 2.00 2.00
d22 11.62 8.23 2.00
d25 12.23 15.61 21.84
d27 17.60 10.95 2.52
d29 13.87 20.52 28.95
d31 4.65 4.65 4.65

Zoom lens data group Starting surface Focal length
1A 1 276.78
1B 4 160.31
1 1 104.18
2 6 -45.08
3 11 123.33
4 17 56.14
5 23 -39.42
6 26 43.44
7 28 -63.28
8 30∞

[Numerical Example 5]
Unit: mm

Surface data surface number rd nd νd
1 92.854 2.90 1.85478 24.8
2 76.349 9.34 1.43875 94.7
3 2132.413 (variable)
4 91.057 4.86 1.49700 81.5
5 669.503 (variable)
6 -312.420 1.50 1.76200 40.1
7 60.146 3.74
8 -85.768 1.50 1.61772 49.8
9 54.938 3.96 2.00069 25.5
10 673.930 (variable)
11 (Aperture) ∞ 1.00
12 73.511 4.37 1.85150 40.8
13 -169.528 1.85
14 -54.502 1.50 1.76182 26.5
15 46.881 0.56
16 46.167 4.86 2.00100 29.1
17 -1705.381 (variable)
18 -202.840 3.10 2.00330 28.3
19 -57.967 0.20
20 54.407 7.03 1.59522 67.7
21 -37.608 1.70 2.00069 25.5
22 1034.169 (variable)
23 263.032 3.32 1.92286 20.9
24 -58.168 1.30 1.85150 40.8
25 31.744 (variable)
26 44.566 9.23 1.48749 70.2
27 -44.338 (variable)
28 -47.760 1.80 1.74320 49.3
29 -500.000 (variable)
30 ∞ 0.20 1.51633 64.1
31 ∞ (variable)
Image plane ∞

Various data Zoom ratio 2.67
Wide Angle Mid Telephoto Focal Length 73.00 130.00 195.00
F-number 2.88 2.88 2.88
Half angle of view (°) 16.51 9.45 6.33
Image height 21.64 21.64 21.64
Lens length 177.25 211.45 230.53
sk 20.34 27.76 35.90

d 3 1.00 35.20 54.28
d 5 3.53 24.43 36.10
d10 38.22 19.02 2.39
d17 6.30 4.59 9.56
d22 10.84 7.58 2.00
d25 7.73 11.00 16.58
d27 19.68 12.26 4.12
d29 13.79 21.21 29.35
d31 6.42 6.42 6.42

Zoom lens data group Starting surface Focal length
1A 1 274.93
1B 4 211.47
1 1 122.36
2 6 -59.24
3 11 110.01
4 18 77.47
5 23 -45.78
6 26 47.20
7 28 -71.17
8 30∞

Figure 11 shows a digital still camera as an imaging device that uses the zoom lens of each of the above examples as an imaging optical system. Reference numeral 20 denotes the camera body, and reference numeral 21 denotes the imaging optical system constituted by the zoom lens of any of Examples 1 to 5. Reference numeral 22 denotes a solid-state imaging element such as a CCD sensor or CMOS sensor that is built into the camera body 20 and captures the optical image (subject image) formed by the imaging optical system 21. Reference numeral 23 denotes a recording section that records image data generated by processing the imaging signal from the imaging element 22, and reference numeral 24 denotes a rear display that displays the image data.

By using the zoom lens of each embodiment, a small camera with high performance can be obtained.

The camera may be a single-lens reflex camera with a quick-turn mirror, or a mirrorless camera without a quick-turn mirror.

The above-described embodiments are merely representative examples, and various modifications and variations are possible when implementing the present invention.

B1: First lens unit B2: Second lens unit B3: Third lens unit B4: Fourth lens unit B5: Fifth lens unit B6: Sixth lens unit B7: Seventh lens unit

Claims (20)

Arranged in order from the object side to the image side,
The optical system is composed of a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, a sixth lens group having a positive refractive power, and a seventh lens group having a negative refractive power .
When zooming,
The spacing between adjacent lens groups changes,
The first lens group and the second lens group move,
a plurality of lens groups among the third lens group to the seventh lens group move;
At least one of the fourth lens group to the seventh lens group is stationary;
When the focal length of the third lens group is f3 and the focal length of the fourth lens group is f4,
0.440≦f3/f4≦3.443
A zoom lens characterized by satisfying the following conditions. The zoom lens of claim 1, characterized in that the fifth lens group moves during focusing. The zoom lens according to claim 1 or 2, characterized in that the sixth lens group is stationary during zooming. The zoom lens according to any one of claims 1 to 3, characterized in that the fourth lens group is stationary during zooming. The zoom lens according to any one of claims 1 to 4, characterized in that the third lens group consists of two lenses with positive refractive power and one lens with negative refractive power. The zoom lens according to any one of claims 1 to 5, characterized in that the fourth lens group consists of two lenses with positive refractive power and one lens with negative refractive power. Arranged in order from the object side to the image side,
The optical system is composed of a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a negative refractive power, a sixth lens group having a positive refractive power, and a seventh lens group having a negative refractive power .
When zooming,
The spacing between adjacent lens groups changes,
The first lens group and the second lens group move,
a plurality of lens groups among the third lens group to the seventh lens group move;
At least one of the fourth lens group to the seventh lens group is stationary;
13. A zoom lens according to claim 12, wherein the fourth lens group comprises two lenses having positive refractive power and one lens having negative refractive power. When the focal length of the first lens group is f1 and the focal length of the second lens group is f2,
1.440≦f1/｜f2｜≦3.260
8. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the second lens group is f2 and the back focus of the zoom lens at the wide-angle end is wsk,
1.690≦|f2|/wsk≦5.990
9. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the first lens group is f1 and the focal length of the fifth lens group is f5,
1.850≦f1/｜f5｜≦9.230
10. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the sixth lens group is f6 and the focal length of the seventh lens group is f7,
0.340≦f6/｜f7｜≦0.900
11. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the first lens group is f1 and the focal length of the third lens group is f3,
0.590≦f1/f3≦4.110
12. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the first lens group is f1 and the focal length of the seventh lens group is f7,
1.150≦f1/｜f7｜≦3.460
13. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the second lens group is f2 and the focal length of the sixth lens group is f6,
0.720≦|f2|/f6≦2.780
14. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the seventh lens group is f7 and the back focus at the wide-angle end of the zoom lens is wsk,
2.370≦｜f7｜/wsk≦5.650
15. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the second lens group is f2 and the focal length of the third lens group is f3,
0.550≦f3/｜f2｜≦3.560
16. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the second lens group is f2 and the focal length of the zoom lens at the wide-angle end is fw,
0.430≦|f2|/fw≦1.640
17. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the fifth lens group is f5 and the focal length of the zoom lens at the telephoto end is ft,
0.110≦|f5|/ft≦0.310
18. The zoom lens according to claim 1, which satisfies the following condition: When the focal length of the sixth lens group is f6 and the focal length of the zoom lens at the telephoto end is ft,
0.150≦f6/ft≦0.320
19. The zoom lens according to claim 1, which satisfies the following condition: A zoom lens according to any one of claims 1 to 19;
and an image sensor that receives light from the zoom lens.